An atmospheric residue (AR) obtained from crude oil is hydrodesulfurized by an apparatus for direct desulfurization of fuel oil (hereinafter, referred to as a “direct desulfurization apparatus”), and distillates such as desulfurized naphtha, desulfurized kerosene, and desulfurized gas oil and desulfurized fuel oil are formed. Desulfurized fuel oil is used as fuel for boilers for power generation and others as low-sulfur fuel oil C. Desulfurized fuel oil is also used as a raw material used in fluid catalytic cracking (FCC) apparatuses, and light fractions such as fluid catalytically cracked gasoline (hereinafter, referred to as “FCC gasoline”), fluid catalytically cracked gas oil (hereinafter, referred to as “LCO: light cycle oil”), and the LPG fraction are produced.
In recent years, crude oil available as a raw material oil in purification of oil is becoming heavier, and crude oil containing heavy oil in great amounts tends to be used more frequently as the raw material oil. Moreover, the demand for heavy oil is decreasing. For example, the demand for fuel oil for power generation and for boilers is decreasing. The demand for the LCO fraction formed with the fluid catalytic cracking apparatus is also decreasing.
In contrast, the demand for gasoline is increasing, and the demand for the LPG fraction and the naphtha fraction used as a raw material for many petrochemical products such as propylene, butene, and BTX including benzene, toluene, and xylene is also increasing. Therefore, development of technology for producing light fractions such as gasoline, the naphtha fraction and the LPG fraction from heavy oil such as the atmospheric residue is an important problem.
Under such circumstances, hydrocracking methods in which desulfurized fuel oil and desulfurized heavy gas oil obtained by hydrocracking treatment of heavy oil with a hydrodesulfurization apparatus such as a direct desulfurization apparatus and an indirect desulfurization apparatus are further decomposed to increase the amount of production of desulfurized naphtha, desulfurized kerosene, and desulfurized gas oil etc. are under development. In addition, research and development of a method for converting the desulfurized fuel oil and desulfurized heavy gas oil into light fractions such as the LPG fraction, the FCC gasoline fraction, and the LCO fraction by catalytic cracking with a great degree of decomposition by a fluid catalytic cracking apparatus are conducted. In the method, a catalyst obtained by supporting an active metal on a support including a crystalline aluminosilicate is usually used as a catalyst for hydrocracking of heavy oil.
However, the use of the catalyst may provide an insufficient desulfurization activity in contrast to a high conversion. Further, the conversion of components having high boiling points such as a vacuum residue (VR) having a boiling point of 525° C. or higher in the heavy oil has not always been sufficient.
In view of the foregoing, research and development have been performed to solve those drawbacks. For example, there are many reports on a catalyst for hydrocracking of heavy hydrocarbon oil as a catalyst obtained by supporting an active metal on a support made up of a mixture of a crystalline aluminosilicate such as a zeolite for imparting conversion and an inorganic oxide such as alumina for imparting desulfurization activity (see, for example, Patent Documents 1 to 3).
Patent Document 1 discloses a catalyst for hydrocracking of heavy oil obtained by supporting an active metal on a support made up of a specific aluminosilicate supporting iron in an amount of 65% by mass and alumina in an amount of 35% by mass, as a catalyst capable of raising the yield of middle distillates, in hydrocracking of heavy oil.
In addition, Patent Document 2 discloses a catalyst for decomposing heavy oil as a catalyst obtained by supporting an active metal on a support including a zeolite in an amount of 2 to 35% by mass and specific alumina having an average pore diameter of 6 to 12.5 nm in an amount of 65 to 98% by mass.
In addition, Patent Document 3 discloses that a catalyst obtained by supporting an active metal on a support produced by mixing a slurry of a crystalline aluminosilicate and a slurry of an aluminum compound is effective for a conversion reaction of hydrocarbon. Patent Document 3 describes that for a mixing ratio of the slurry of a crystalline aluminosilicate and the slurry of an aluminum compound, the former is 65% by mass, and the percentage of mesopores in the distribution of pores is 49% or smaller.
However, in the above-mentioned catalysts for hydrocracking including a support made up of a crystalline aluminosilicate, alumina, and the like, as described in Patent Documents 1 and 3, when the mixing ratio of the crystalline aluminosilicate in the support is increased, conversion is enhanced, but desulfurization activity becomes insufficient, and as described in Patent Document 2, when the mixing ratio of the crystalline aluminosilicate in the support is decreased and the mixing ratio of alumina in the support is increased, desulfurization activity is enhanced, but conversion becomes insufficient. Thus, catalysts for hydrocracking of heavy oil for which high conversion and high desulfurization activity are simultaneously demanded have been in the situation where none of the catalysts can sufficiently meet the above-mentioned demands.
Thus, there has been a demand for a catalyst for hydrocracking of heavy oil simultaneously having higher conversion and higher desulfurization activity.